Solve the Linear Equation: -2(4+5x) + 3(2-2x) = 8(4-x)

Linear Equations with Negative Distribution

Solve for X:

2(4+5x)+3(22x)=8(4x) -2(4+5x)+3(2-2x)=8(4-x)

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find X
00:04 Open parentheses properly, multiply by each factor
00:27 Combine like terms
00:44 Arrange the equation so that X is isolated on one side
01:02 Combine like terms
01:06 Isolate X
01:17 Factor 34 into 17 and 2
01:22 Factor 8 into 4 and 2
01:28 Simplify what's possible
01:32 This is the solution to the problem

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve for X:

2(4+5x)+3(22x)=8(4x) -2(4+5x)+3(2-2x)=8(4-x)

2

Step-by-step solution

To solve this equation 2(4+5x)+3(22x)=8(4x)-2(4 + 5x) + 3(2 - 2x) = 8(4 - x), let's work through it step by step:

Step 1: Distribute the constants into the parentheses:

  • Distribute 2-2 in 2(4+5x)-2(4 + 5x):
  • 2(4)+2(5x)=810x -2(4) + -2(5x) = -8 - 10x
  • Distribute 33 in 3(22x)3(2 - 2x):
  • 3(2)+3(2x)=66x 3(2) + 3(-2x) = 6 - 6x
  • Distribute 88 in 8(4x)8(4 - x):
  • 8(4)8(x)=328x 8(4) - 8(x) = 32 - 8x

Step 2: Substitute the distributed expressions back into the equation:

810x+66x=328x -8 - 10x + 6 - 6x = 32 - 8x

Step 3: Combine like terms on each side of the equation:

  • On the left side, combine 8-8 and 66, and 10x-10x and 6x-6x:
  • 216x -2 - 16x
  • The right side remains:
  • 328x 32 - 8x

Step 4: Rewrite the equation:

216x=328x -2 - 16x = 32 - 8x

Step 5: Isolate xx by first adding 8x8x to both sides to get rid of 8x-8x on the right:

216x+8x=32 -2 - 16x + 8x = 32 28x=32 -2 - 8x = 32

Step 6: Add 22 to both sides to isolate the x term:

8x=34 -8x = 34

Step 7: Divide both sides by 8-8 to solve for xx:

x=348=174 x = \frac{34}{-8} = -\frac{17}{4}

Therefore, the solution to the equation is x=174 x = -\frac{17}{4} .

3

Final Answer

174 -\frac{17}{4}

Key Points to Remember

Essential concepts to master this topic
  • Distribution: Multiply each term inside parentheses by outside coefficient
  • Technique: -2(4+5x) becomes -8-10x, keeping all signs correct
  • Check: Substitute x = -17/4: both sides equal 66 ✓

Common Mistakes

Avoid these frequent errors
  • Sign errors when distributing negative coefficients
    Don't forget to change signs when distributing negatives like -2(5x) = -10x, not +10x! This flips the equation completely and gives wrong answers. Always distribute the negative sign to every term inside the parentheses.

Practice Quiz

Test your knowledge with interactive questions

Solve for x:

\( 2(4-x)=8 \)

FAQ

Everything you need to know about this question

Why do I keep getting the wrong sign when distributing?

+

Negative distribution is tricky! Remember that 2(4+5x) -2(4+5x) means multiply each term by -2. So 2×4=8 -2 \times 4 = -8 and 2×5x=10x -2 \times 5x = -10x .

How do I combine like terms correctly?

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Group your x-terms together and your constant terms together. For example: 10x6x=16x -10x - 6x = -16x and 8+6=2 -8 + 6 = -2 .

What's the best way to isolate x?

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Move all x-terms to one side and all constants to the other. Add or subtract the same amount from both sides to keep the equation balanced.

My answer is a fraction - is that normal?

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Yes! Fractional answers are completely normal for linear equations. x=174 x = -\frac{17}{4} is a valid solution. Always leave fractions in simplest form.

How can I check if -17/4 is really correct?

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  • Substitute x=174 x = -\frac{17}{4} into the original equation
  • Calculate both sides carefully
  • If both sides equal the same number, your answer is right!

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